1. Technical Field
The present invention relates to a method and apparatus for collecting sterile urine samples for analysis. More particularly, the present invention relates to the sterile collection of the midstream portion of void urine in a simple manner, with inexpensive apparatus, and without spillage or dripping of the forestream and terminal portions of the void.
2. The Prior Art
In collecting urine samples for medical testing and analysis, it is important that the collected sample be as free from contaminants as possible. Contaminants in the urethra and other areas of the urinary tract render straightforward collection of sterile samples somewhat difficult. The problem of contamination is even greater for women patients than for men because of the location of the urethral opening just superior to the vaginal opening. Secretions and other contaminants which collect in the vaginal area, including the labia majora and labia minora, are a particularly troublesome source of urine specimen contamination. It is therefore desirable that the collected sample consist of a midstream portion of a urine void so that the urethra and other areas of the urinary tract, as well as the related portions of the vaginal area, can be flushed out with the initial or forestream portion of the void before the sample for analysis is passed for collection. However, midstream urine collection is not an easy procedure, primarily because it is difficult for a patient to interrupt a void stream so as to pass only part of the stream before collecting sample. As a consequence, numerous devices have been proposed in the prior art for automatically collecting midstream portions of a urine void. Examples of these devices may be found in U.S. Pat. Nos. 3,583,388 (Hovick), 3,635,091 (Linzer et al.), 3,722,503 (Hovick), 3,750,647 (Gleason et al.), 3,830,107 (Linzer et al.), 3,943,770 (McDonald), 3,982,898 (McDonald), 4,040,791 (Kuntz), 4,094,020 (Franklin), 4,276,889 (Kuntz et al.) and 4,331,162 (Kuntz et al.). In spite of these devices, problems still exist in the art of midstream urine collection. For example, certain of these prior art midstream collection devices require relatively complex structure which form-fits a woman's vaginal area. Such devices, apart from their complexity and expense, are psychologically rejected by many women patients who simply prefer not to use them. Others of these patented devices require expensive and/or bulky structure to select the midstream portion of a void. Still others have inherent leakage problems wherein the initial void portion and/or the terminal void portion tends to leak or drip after the midstream sample container has been disconnected or disassociated from the rest of the apparatus. For example, the devices disclosed in the aforementioned U.S. Pat. Nos. 4,276,889 and 4,331,162 (Kuntz et al.) direct the forestream or initial void portion into a chamber having a bleed hole in its bottom. Experience has shown that urine tends to drip from this bleed hole after the specimen container has been removed and during disposal of the chamber. This dripping is not favored by medical personnel who have to handle the device.
The aforesaid Kuntz et al patents rely on a build-up of urine level in the initial void bleed chamber before the urine overflows into a surrounding toroidal specimen container. It is possible, particularly in the case of patients with urinary tract disorders, that the bleed rate from the chamber bleed hole will exceed or equal the patient's void rate; or, the patient's void rate may exceed the bleed rate by too small a difference for the level in the chamber to reach the overflow opening. Under such circumstances, the device cannot collect the desired midstream sample.
Many of the prior art midstream collection devices rely on directing the forestream portion of the void into a chamber and then diverting or overflowing the midstream portion into a specimen container when the urine level in the chamber reaches some predetermined level. In such devices, unless the assembly is held absolutely still the forestream portion is jostled and tends to intermix to some degree with the diverted or overflowing midstream portion. This intermixing results in contamination of the midstream portion by contaminants in the forestream portion.
Another problem of prior art midstream urine collection units relates to the difficulty with which the midstream specimen container is disassociated from the rest of the unit and transported to the analysis location. In many prior art units the entire unit and not just the specimen container must be transported. In units where the specimen container can be relatively easily disassociated from the rest of the unit, the disassociated specimen container is not readily sealed without contaminating the collected specimen.